Selenium-alloyed tellurium oxide for amorphous p-channel transistors

Compared to polycrystalline semiconductors, amorphous semiconductors offer inherent cost-effective, simple and uniform manufacturing. Traditional amorphous hydrogenated Si falls short in electrical properties, necessitating the exploration of new materials. The creation of high-mobility amorphous n-type metal oxides, such as a-InGaZnO (ref. 1), and their integration into thin-film transistors (TFTs) have propelled advancements in modern large-area electronics and new-generation displays2–8. However, finding comparable p-type counterparts poses notable challenges, impeding the progress of complementary metal–oxide–semiconductor technology and integrated circuits9–11. Here we introduce a pioneering design strategy for amorphous p-type semiconductors, incorporating high-mobility tellurium within an amorphous tellurium suboxide matrix, and demonstrate its use in high-performance, stable p-channel TFTs and complementary circuits. Theoretical analysis unveils a delocalized valence band from tellurium 5p bands with shallow acceptor states, enabling excess hole doping and transport. Selenium alloying suppresses hole concentrations and facilitates the p-orbital connectivity, realizing high-performance p-channel TFTs with an average field-effect hole mobility of around 15 cm2 V−1 s−1 and on/off current ratios of 106–107, along with wafer-scale uniformity and long-term stabilities under bias stress and ambient ageing. This study represents a crucial stride towards establishing commercially viable amorphous p-channel TFT technology and complementary electronics in a low-cost and industry-compatible manner.

inverse Fourier-transformed EXAFS spectra after curving-fitting process at Te K-edge and Se Kedge, respectively.Supplementary Tables 1 and 2 present the EXAFS structural parameters for Te K-edge and Se K-edge k 3 -weighted EXAFS spectra of Se-alloyed Te-TeO x sample, respectively.In order to obtain the total amplitude reduction factor, S 0 2 , the first shell coordination numbers of metallic Te and TeO 2 are fixed to 2. And each value in parentheses means the uncertainty evaluated from calculation process.

2) Parameters information:
Supplementary Table  To enable the clear comparisons and improve the evaluation of data quality, both the original EXAFS spectra and the imaginary part of Fourier Transforms (FTs) are provided in Supplementary Fig. 4.
Pohang light source (PLS-II) with top-up mode operation under a ring current of 250 mA at 3.0 GeV.The monochromatic X-ray beam could be obtained using liquid-nitrogen cooled Si(311) double crystal monochromator (Bruker ASC).For Te (31814 eV) and Se (12658 eV) K-edge XAFS measurements, X-ray absorption spectroscopic data were recorded in fluorescence mode with 7 channels silicon drift detector (SDD, Rayspec Ltd.) as photon detector.Higher order harmonic contaminations were eliminated by detuning to reduce the incident X-ray intensity by ~20%.Energy calibration has been carried out with reference Te and Se metal powders.
][3][4] Using AUTOBK module in UWXAFS package 5) , the k 3 -weighted Te K-edge and Se K-edge EXAFS spectra, k 3 χ(k), have been obtained through background removal and normalization processes.The k 3 χ(k) spectra have been Fourier-transformed (FT) in the k ranges between 3.5 and 14.0 Å -1 (Te K-edge) and 15.0 Å -1 (Se K-edge).The experimental FT spectra have been inversely Fourier-transformed with the hanning window function in the r space range between 1.0 and 3.2 Å (Te K-edge) and 3.0 Å -1 (Se K-edge).To determine the EXAFS structural parameters for the first bond pairs, the curve-fitting process has been carried out by using the single bonding model.Theoretical single scattering paths of the first shells around central Te element have been calculated with FEFF9 code [6][7] under the space groups of P 41 21 2 for the tetragonal TeO 2 model, P 31 2 1 for the trigonal Te metallic, C2 for the monoclinic TeSe 2 , P 31 2 1 for the trigonal Se metallic. I the EXAFS curve fitting process with FEFFIT module, total amplitude reduction factor, S 0 2 , were fixed to 0.7 for the Te K-edge XAFS and 0.9 for the Se K-edge XAFS, which were obtained after EXAFS fitting for metallic Te and Se EXAFS spectra with constant two coordination numbers.The EXAFS structural parameters, interatomic distance (r), coordination numbers (N), Debye-Waller factor (σ 2 ), have been determined within allowed R-factor value which is quality of the fit with {ReΔχ k 2 +ImΔχ k 2 }/{Re(χ kdata ) 2 +Im(χ kdata ) 2 }, where χ(k) is EXAFS-function) and Δχ(k) means χ(k) data χ(k) best-fitted .For k-r space correlations, Morlet wavelet-transformed EXAFS have been also obtained with proper values of η and σ in equation spectra [8][9] as follows; where the η is the frequency of the oscillation functions and the σ is the half width.
. EXAFS Structural parameters for Te K-edge k 3 -weighted EXAFS spectra of Se-alloyed Te-TeO x sample calculated from EXAFS curve-fitting process.
*In order to obtain the total amplitude reduction factor, S 0 2 , the first shell coordination number of metallic Te is fixed to 2. And each value in parentheses means the uncertainty obtained from calculation process.**Rfactorvaluewhich is quality of the fit determined with {ReΔχ k 2 +ImΔχ k 2 }/{Re(χ kdata ) 2 +Im(χ kdata ) 2 }, where χ(k) is EXAFS-function) and Δχ(k) means χ(k) data -χ(k) best-fitted .Supplementary Table2.EXAFS Structural parameters for Se K-edge k 3 -weighted EXAFS spectra of Se-alloyed Te-TeO x sample calculated from EXAFS curve-fitting process.